/*
 * Copyright 2008 Christopher Davies
 * 
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 * 
 *     http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.googlecode.textish.tokenizer;

import java.util.Iterator;
import java.util.List;

/**
 * Tokenizes a list of {@link WordToken}s and {@link CharToken}s into a list
 * of {@link LineToken}s.
 * 
 * @author cgdavies
 * 
 */
public class LineTokenizer implements ITokenizer {

	public void tokenize(CharSequence context, List input, List output) {
		TokenBuilder lineBuilder = LineToken.createBuilder();

		for (Iterator it = input.iterator(); it.hasNext();) {
			IToken token = (IToken) it.next();

			if (token instanceof WordToken) {
				lineBuilder.append(token);
			}
			else if (token instanceof CharToken) {
				char ch = context.charAt(((CharToken) token).getStartIndex());

				// If this is a newline character, build the line token, append
				// it and throw away the character token UNLESS the current
				// lineBuilder has no children (this indicates a repetition of
				// newline characters, which we need to know about to build
				// paragraphs).
				if (ch == '\n') {
					IToken line = lineBuilder.build();

					if (line != null)
						output.add(line);
					else
						output.add(new EmptyLineToken(token.getStartIndex()));
				}
				else
					lineBuilder.append(token);
			}
			else
				throw new UnexpectedTokenException(token.getClass());
		}

		IToken lineToken = lineBuilder.build();
		if (lineToken != null)
			output.add(lineToken);
	}

}
